Importance

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Abstract

A raster scan control system (18) for use with a charged-particle beam delivery system (20) provides precise control of large currents driving an inductive load. The beam delivery system includes a nozzle through which a charged-particle beam (24), such as a proton beam, passes prior to being directed to a target (32). The nozzle includes both fast and slow sweep scan electromagnets (204, 208) that cooperate to generate a sweeping magnetic field that steers the beam along a desired raster scan pattern at the target. The electromagnets are driven by large currents (213, 215) from the raster scan control system. The raster scan control system includes both fast and slow power amplifiers (212, 214) for delivering the desired large currents to the fast and slow electromagnets, respectively; monitoring means (206, 210) for monitoring the magnetic fields; sensing means (212, 230) for sensing the large currents; feedback means for maintaining the magnetic fields and large current at desired levels; out of tolerance means for automatically causing the servo power amplifiers to steer the beam away from the target area in the event the error signal becomes excessive; a programmable raster generator (80) for providing the fast and slow power amplifiers with a raster scan signal (216, 218) that defines the desired raster pattern; and a power supply (74) for delivering the requisite power to the power amplifiers and other components.

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First Claim